Most NFL players are millionaires, though not all know how to handle the financial stresses and temptations that come with their riches.

"That's one of the things you play for is, obviously, the fame and the fortune," notes George Martin, president of the NFL Alumni Association and one-time Super Bowl champion with the New York Giants, where he played for 14 seasons. "To be able to receive the sums of money that young guys are receiving today, it’s wonderful, it’s magnificent. And if done properly it could give them a great, great start on life. If not done properly, it could lead to a lot of regrets throughout the remainder of their life."

But as the NFL lockout drags on, a few football players have said that life on the gridiron is really like being ... a slave.

Pittsburgh Steelers running back Rashard Mendenhall tweeted, "Anyone with knowledge of the slave trade and the NFL could say that these two parallel each other."

Miami Dolphins running back Patrick Cobbs told a Miami radio station, "I wouldn't say slave.. obviously, we all love to play the game. But I think at times we are slaves. They tell us to jump and we jump. Most of the time we ask them how high.... I can see where [Peterson] is coming from. So that's like slaves. But we're not slaves because we get paid pretty well to do it."

That view is hardly universal.

“I don't know how one can even defend saying that it was a fair comment," responded Daniel Kaplan, who covers the financial side of the NFL for Sports Business Journal. Kaplan and others question how NFL players, whose average salaries are estimated at nearly $2 million dollars – with a $300,000 per season minimum for rookies - could even equate the working conditions of slaves with millionaire athletes.

"There are things about being a professional football player that I don't think many of us could put up with," he says. "Certainly, the way these contracts are structured, so that if they get injured they don't get a lot of their money, that the teams can cut them at will, if they sign a contract they can't break it, it's those sorts of things that lead to the frustrations I am sure Adrian Peterson feels, but certainly, it’s not slavery."

Others point to what they say are tough NFL restrictions on players and the nature of the sport.

"Football players are punished in a way, physically, that is unseen in any other pro-sport and that gives rise to some of the tension," notes Sports Illustrated reporter Pablo Torres, who wrote an in-depth investigation of players' lives titled "How (And Why) Athletes Go Broke." He also says, "Once a player signs a contract he is not entitled to that money if he is injured, if he is cut from the team, that is something unique to the NFL." But despite the restrictions, he thinks, "The term 'slaves,' in any case, is so loaded historically and weighted with so many things it is a bad choice of words in this kind of discussion."

The NFL will not speak to the slavery comments of the three players, but told Fox News the league is spending about $4.5 billion a year collectively on players' costs, far more than any other league spends on players. They also told us that the owners have offered compensation to the players of nearly $20 billion a year for the next three years.

The NFL also says, "About half of all player compensation is guaranteed through signing bonuses," and "like any sports league, a team can release and sign players to improve the team."

But some point out the lure of getting and spending big money can sometimes prove as disappointing as a quarterback sack.

"If you are 22 or 23 years old, getting checks for several hundred thousand dollars a week is pretty heady stuff," says Robert Boland, a professor of sports management at New York University's Tisch Center for Hospitality, Tourism and Sports Management. "The fact that these guys really live above their means isn't a surprise, but it’s very sad, which is why the pressure of a lockout really hurts them and why they need to get back to play and maximize their career. They really need to work to earn their money."

"Who of us coming out of college at 20 or 21 had the worldly experience to handle millions of dollars?" asks Martin, the NFL Player alumni head. "Few of us, if ever, could do that."

Martin says he has seen it all. "The excessive cars, obviously the jewelry or the bling as they call it, the excessive vacations, the parties," and he says the challenge is for players to learn financial responsibility, considering the average pro career lasts less than four years.

"If not done properly, it could lead to a lot of regrets throughout the remainder of their lives. If they do not handle their investments wisely, if they do not handle the fortunes that they receive, if they don't handle those sums of money as an intelligent adult, and that's why we call it professional athletics as opposed to amateur athletics, then it could lead to a lot of problems and heartaches down the road."

Some say the public image of spendthrift players is not at all accurate.

"For the most part they are not really that outrageous," says Wes Bridges, an agent for NFL players at Enter-Sports Management. "There are not a lot of trips, there aren't a lot of gold and bling, I mean that is something you hear the stories out there. Our experiences have been the players are pretty down to earth in their approach."

He says that he finds, "With our players, as long as they are educated and they are told the benefit of saving, the need to save. The old adage, the NFL stands for 'Not For Long,' so money that you have, you have to conserve."

But with the lockout stretching into Week 12, there are now stories of players moving in with parents, parents of their wives or taking out huge loans until the paychecks start flowing when the kickoffs resume.

"NFL players are most like lottery winners," says Torres, because they are "guys who came into income very suddenly, who do not have the financial literacy or equipment to deal with that money, and they are expected to be released to the entire world and be productive, financial citizens and that just doesn't happen, and that is historically not been the case."

Martin, the veteran former player, has a lesson for his younger counterparts.

"I think the worst example is coming in and thinking that this will last forever and not being responsible for those great sums of money that you get. Going out and saying, if I can use this term, they want to live fast and die young, I mean that kind of attitude. There really is not place in this industry for attitudes like that. If you are going to be a professional athlete, if you are going to put on that uniform, you have a responsibility not only to yourself, but to teammates, to your club, and most of all to your community. You have to be professional in every sense of the word."

The next court hearing, in St. Louis on Friday, could help determine if and when the NFL season can get under way.

Eric Shawn is a New York-based anchor and senior correspondent for FOX News Channel (FNC). He anchors "America's News Headquarters" on Sundays from 12 p.m. to 1 p.m. ET. and “Sunday Morning Futures with Maria Bartiromo.” He anchors frequently during the week on the Fox News Channel and reports on politics, terrorism, and foreign affairs. Shawn has provided live coverage from both the Democratic and Republican National Conventions since 1992. In 2004 he led the Fox News investigative team that uncovered new evidence in the murder of Jimmy Hoffa, based on the claims of hit-man Frank Sheeran. Click here for more information on Eric Shawn.